A common type of injury, especially among athletes, is the complete or partial detachment of soft tissue including tendons or ligaments from bone. Tissue detachment may occur during a fall, by overexertion, or for a variety of other reasons. Surgical intervention is often needed, particularly when tissue is completely detached from its associated bone. Currently available devices for mechanical tissue reattachment in these and other orthopedic repairs include screws, staples, tacks and suture anchors. Suture anchors generally have an anchoring body for establishing a firm connection to bone, and one or more suture-retaining feature such as an eyelet or other passage that facilitates connection to and positioning of the separated tissue, to effect its repair to the bone.
One objective in improving the outcome of surgical procedures to repair a tissue detachment is to minimize surgical trauma to the patient, that is, to minimize trauma caused by the surgical procedure and not associated with the original injury. Progress in this field in recent years has included the introduction of minimally invasive surgeries, including arthroscopic surgeries where, for example, an anchor loaded with suture and mounted on an inserter device can be passed to a surgical site and fixed to bone via a surgical cannula positioned through a small opening in the patient's skin, thereby minimizing the size of the associated surgical incision and associated trauma.
The design of the suture anchor itself, including how it is fixed in bone and how it retains suture, is very important to surgical outcome, as well as to reducing the difficulty of performing technically challenging arthroscopic procedures, where the surgeon is required to manipulate sutures, anchors, soft tissue and bone, using specialized tools that must be operated through the narrow diameter cannula. Tying knots at a surgical site that is accessed only through a cannula can be particularly challenging. Early suture anchor designs typically routed suture slidingly through an eyelet in the anchor body so the suture could be tied between the anchor and soft tissue using surgical knots, commonly after drawing the damaged tissue to the anchor in bone.
Some more recent anchors are configured to retain suture without using knots, either via a unidirectional suture passage through the anchor, or using a mechanism that actively clamps the suture to prevent suture sliding through the eyelet after completion of the repair. Although some knotless suture anchors have been developed and can somewhat simplify a surgeon's tasks in minimally invasive surgeries, it remains challenging to provide anchors with which soft tissue can be drawn to a desired location on bone independently of locking the anchor body itself into the bone.
Further, many current suture anchors and especially many knotless anchors require a substantial depth of penetration into the bone for fixing the anchor, the depth often greatly exceeding a diameter or other cross sectional dimension of the anchor. In some situations such anchors are longer in their direction of insertion into bone than would be optimal for patient safety, for example, in some shoulder and spinal surgeries where adequate depth for the anchor or an opening to receive the anchor within the bone may not be available or easily evaluated in advance by the surgeon.
Therefore there is a need for improved anchoring devices that provide knotless attachment of suture or soft tissue to bone, as well as suture anchors designed for minimum penetration into bone.